When the Irish Tenors burst upon the international music scene in 1998, they quickly became one of the most successful exports from the Emerald Isle since Guinness. Columbus did its part: The harmonious trio has played to huge crowds each of the three previous times it has toured here.

Not last night. The tenors — Finbar Wright, Anthony Kearns and now John McDermott, replacing Ronan Tynan — filled about half the Palace Theatre on what reportedly was the first stop on their latest North American tour.

In truth, the concert, especially the first half, sounded like a bad rehearsal. The orchestra played with all the enthusiasm and polish of folks sight reading, which some might have been, and the conductor — the only one onstage all night who broke a sweat — labored valiantly to keep things tidy.

The tenors took the entire opening hour just to warm up. Kearns tried to joke about it but nobody, including him, laughed much. When all three were onstage together, McDermott sometimes stood awkwardly to one side without singing, since he didn’t appear to know all the words.

A quick trip to the Blarney stone for him, hurry!

It’s a tribute to the trio’s enduring appeal that the steadfast crowd showed even tepid appreciation. They’re a patient lot, and to a degree, patience was rewarded in the second half.

A jolt of reality must have shot through the performers during intermission because the orchestra finally got it together, the tenors’ voices finally opened up and all three finally began to sing out with the earnest emotions that have been their hallmark. Bugs in the sound system also disappeared, a help to be sure.

Still, it was a program long on old-fashioned Irish ditties and short on the kind of inspiration that helped make this talented trio resonate deeply with a wide spectrum of listeners, Celtic and otherwise.

This is the group’s first trip to Columbus since Tynan spun off to go out on his own. He’s sorely missed. He was not just a powerful voice, he was a powerful presence — with a personality and magnetism that stretched across the footlights.

Without him, the Irish Tenors are what the Three Tenors would have been without Luciano Pavarotti: three tenors. Without Tynan, their star is gone, and so is their heart.

Fans of the Irish Tenors want the old style, the old Irish Tenor soul back, whoever is in the group. Say a prayer to St. Patrick.